Suggestion, try to get into the habit of going by weight not volume when feeding.
Reason being, your feeding a feed that is grains and crumbles and it takes up more volume than a mash type feed but a pound of feed is a pound of feed no matter the type.
Another way to look at it is this, one's persons 1/4 cup of feed could be another persons 1 cup of feed when you weigh it out and in the end there eating the same amount of nutrition.
Now after saying all that, how much scratch and peck feed do your birds eat when there feed is not fermented, is it the same as when it is fermented? I have a funny felling that fermenting feed may lower the Metabolisable Energy.